ˌ ̷ ̷ ̷ ̷ˈ ̷ ̷ēəm noun
( plural ommatid·ia -ēə)
Etymology: New Latin, from Greek ommat-, omma eye + New Latin -idium
: one of the elements corresponding to a small simple eye or ocellus that make up the compound eye of an arthropod and that typically consist of an external corneal lens beneath which is a crystalline cone and below it a rhabdom which is enclosed in a sensitive retinula protected by pigment